Remove trailing space in CSSStyleSheet::AddRule() (servo#36383)

-Remove trailing space in CSSStyleSheet::AddRule()

Testing: The change made does not require testing
Fixes: servo#36380

Signed-off-by: Uthman Yahaya Baba <[email protected]>

Author: uthmaniv

components/script/dom/cssstylesheet.rs

@@ -181,7 +181,7 @@ impl CSSStyleSheetMethods<crate::DomTypeHolder> for CSSStyleSheet {
         } else {
             rule.push_str(" { ");
             rule.push_str(block.str());
-            rule.push_str(" } ");
+            rule.push_str(" }");
         };
 
         // > 6. Let *index* be *optionalIndex* if provided, or the number of CSS rules in the stylesheet otherwise.